-Psoriasis is a significant health problem for upwards of 5 million Americans. Psoriasis is a hyperproliferative disorder of the epidermis. Cutanogen Inc., has identified parathyroid hormone-related peptide (PTHrP) as a substance produced by skin cells which is responsible for regulating the proliferative activity of the epidermis. A parathyroid hormone-related peptide agonist, parathyroid (1-34)[PTH(1-34)], was found to be a potent inhibitor of keratinocyte proliferation in vitro and decreased epidermal proliferation in vivo in mice. Normal human skin produces PTHrP whereas psoriatic epidermis does not. Therefore, it is reasonable to consider using the PTHrP receptor agonist (PTH (1-34) as a therapeutic modality for reversing the hyperproliferative state of the epidermis in psoriasis thereby resulting in a safe new effective treatment. The goal of this pilot study is to determine the therapeutic efficacy and safety of the topical administration of the PTHrP/PTH receptor agonist PTH (1-34) for the treatment of plaque psoriasis in adults. The study will be conducted in a randomized double blind right/left-sided controlled fashion for the dose escalation study and in a self-controlled manner for the large area clinical efficacy and safety trial. Results from this pilot study will provide important safety and efficacy data for the determination of whether a phase II clinical trial should be initiated. PROPOSED COMMERCIAL APPLICATION: NOT AVAILABLE